Following surgery to the foot, and particularly surgery to the metatarsophalangeal area, it is desirable to apply a splint to support the foot and prevent flexing of the operative joint. Various approaches have been attempted in the design of such splint, such approaches being directed to relieving the forward portion of the foot from flexing of the joint which would occur during walking.
One early approach to such type of device is disclosed in U.S. Pat. No. 2,725,648, a splint or "rocker" device which, in one embodiment, is attached to the undersole of a conventional shoe. The rocker is designed for use without a shoe and comprises a block of rigid material having a convex, arch-supporting upper surface, and a convex, rocker-like ground-engaging surface.
In a later approach, as shown in U.S. Pat. No. 4,425,721, there is provided a walking sole to be utilized under an immobilizing bandage of the lower leg, to maintain all foot joints in a rigid condition. The ground-engaging surface thereof is formed in three flat portions, each of which merges into the adjacent portion to form a sole that approaches the normal walking motion.
Problems with such devices as described hereinabove, and with others similar thereto, are created by the lack of recognition that the configuration of the upper, foot supporting surface of a sole is critical to maintaining the foot in a proper post-operative position until healing is complete. Further, and most importantly, in certain types of operations, it is important to relieve the pressure on the operative area which occurs when the weight of the person is placed on the feet. As long as any portion of the foot is engaged thereunder by a portion of the foot supporting surface of the sole, pressure on the foot will occur.
It was therefore to the development of an improved splint which would reduce pressure on the foot while inducing a proper walking motion, that the present invention is directed. It is recognized that some of the prior art devices were relatively successful at improving the walking movement of the post-operative patients; and that some devices aided in retaining the foot in a rigid condition. However, none of the known devices was adequate to accomplish these results, and to eliminate pressure from underneath on the area that had been operated upon.
The present invention is directed to a surgical splint that substantially eliminates pressure on the operative joint, and at the same time encourages a walking motion that is relatively normal. The device accomplishes these objectives through a highly improved design which includes a recess or depression in the foot supporting surface of the sole immediately beneath the operative area that causes the sensitive area to be disengaged or floated from the foot supporting surface of the sole. In a preferred embodiment, the device further includes a ground-engaging surface having a slightly upturned front portion underlying the metatarsophalangeal joint.
Additionally, there is provided an improved upper which is cut slightly higher to help retain the heel of the foot in place, and which is contoured across the dorsum of the foot to relieve pressure from the splint itself.
The overall design is such that the necessity for a cast in addition to the splint is substantially eliminated because it is now possible to "float" the metatarsophalangeal joint, thereby relieving any pressure thereto. As will be detailed below, along with the description of all angles and lines, the splint generally includes a wooden or plastic sole portion with a leather upper. The sole is further provided with an upper, foot-supporting surface and a lower, ground-engaging surface.
The upper surface of the sole includes generally a rear portion for supporting the heel and arch areas of the foot and a forward portion underlying the ball and metatarsal areas of the foot. This upper surface is essentially in the shape of the foot with the rear portion being somewhat narrowed relative to the forward or anterior portion. The outer edges at the heel are slightly elevated to support the heel and prevent lateral rocking thereof. The forward section of the rear portion includes a convex area which supports the arch of the foot.
The anterior portion of the upper surface of the sole includes a recess immediately beneath the areas which were operated on to eliminated pressure and flexing of the metatarsal joint during walking. These areas will generally be described herein as they are designed for splints and adapted for use after surgery to the first metatarsal joint (the big toe). However, the sole can be structured to relieve pressure from any of the other metatarsal joints (the other toes).
The recess is carved out of or molded into the upper surface of the sole, underlying the toe and metatarsal joint of the foot which has been operated upon. The weight or pressure on surrounding portions of the foot is borne by the sole which underlies the ball of the foot and by the convex area which is adjacent the metatarsal recess. This convex area lies adjacent and parallel to the recess, generally along the second and third metatarsals, assuming the recess is beneath the first metatarsal joint.
So designed, the weight of the anterior portion of the foot is supported by the ball and the medial portion of the foot, and the operative area "floats" free of pressure or weight thereto.
While the ground-engaging surface of the sole is designed to aid in walking in a nearly normal manner, it is also designed to require a slight lifting of the foot at each step. This prevents the rolling forward or rocking motion which normally occurs when walking. Elimination of this rocking motion (which prior art devices encourage) further limits pressure on the operative joint.